A few months ago, fashion magazines began making excited predictions about the "return of grown-up fashion". No more, they promised, would the shops be full of flouncy tunics and oversized smocks that made women look as if they were en route to their own christening. Instead, it would all be about "the female form", with designers emphasising - instead of attempting to obliterate - breasts and backsides. And to an extent, the magazines were right. The clothes for this autumn/winter do emphasise a woman's body. But fashion is an industry of extremes, and this new emphasis on the figure is less about womanly clothes than - and possibly you saw this one coming - fetish wear.

At Dolce & Gabbana, metallic cocktail dresses were cinched in with belts wide enough to crush the entire ribcage. Alexander McQueen showed moulded latex armour mimicking breasts and stomach, and thigh-high boots were so tight they looked painted on. Last season's chunky wedges have been dropped in favour of madam-like, spiky ankle boots; and grannyish quilted It-bags now come in blindingly shiny leather, which one friend describes as "call-girl patent".

Even Burberry and Mulberry - better known for more of a sepia-hued, Mitfordian image than a metal-studded one - have jumped on the fetish bandwagon with the enthusiasm of a rogue Tory MP. At the former, ladylike gloves have been swapped for heavily stitched leather ones that tip towards the scary side of the fence. Mulberry, meanwhile, has gone for the style hell for, um, leather, knocking out its popular Bayswater bag in lurid patent; girlish tea dresses have been pushed aside for leather shifts with chunky zips. It's been a while since I read it but I can't recall those featuring in Love in a Cold Climate. Even the advertising has changed. Instead of its nostalgic campaigns of yore, Mulberry models glower in thick red lipstick while angrily gripping or seductively stoking their giant shiny bags.

"We've been through a period where everything has been soft and girly and I think this mood is a reaction to that. You instinctively want to go in the opposite direction," says Christopher Bailey, Burberry's creative director.

Some designers claim a political precedent. Bailey, for example, suggests that "[we are at a] moment in the world where we desire the idea of protection and armour". Others say this trend expresses respect for "strong women", though it's rather odd that such professed awe results in immobilising stilettos and rib-breaking dresses.

The cover of this week's Grazia, a magazine that proudly takes fashion to the mainstream, is the final proof that the fetish look is reaching the mass market. Under the cover line "What's in now" are photos of models in extra-tight dresses, a patent ankle boot that wouldn't look out of place on the foot of a whip-wielding woman in an establishment with lots of poles and low lights and, most disturbingly, purple lipgloss.

This is not the first time designers have come over all fetishistic: Vivienne Westwood was a supporter of the look in the 70s, unsurprisingly for a woman who once ran a shop called Sex. Off the catwalks, influential photographers such as Guy Bourdin and Helmut Newton, also in the 70s, were never averse to putting a model in a saddle. But now the look has become mass as opposed to niche. As Harriet Quick, the fashion features director at Vogue, says evocatively, fetish has "gone full flavour". Yet while a move away from infantilising smock dresses is undoubtedly welcome, there is something dubious about the industry's belief that the only other option for a woman is to dress as if she charges by the hour. A child or a madam: ladies, those are your choices.

Tellingly, when I ask Gareth Pugh - who helped to instigate the look this time round with body suits made of what appears to be Cellophane - why he thought these clothes would appeal to modern women, he replied with commendable candour: "I wasn't thinking about what would sell; I was thinking about what would look good in a fashion show."

But perhaps any scepticism is indicative of instinctive prudishness. After all, just look what a black dress with safety pins did for Elizabeth Hurley. Moreover, Quick wore a "Marios Schwab taffeta round-neck black shift with two half-moon cut-outs above the breasts" to the Serpentine summer party last month. It was, she says delightedly, "very Helmut Newton" but then adds, no doubt voicing many women's fears, "Wear at your peril".